When initially questioned about the death of her 6-day-old child, Koistinen told police investigators that she accidentally fell asleep on top of her.

But when an autopsy revealed that the child may have been intentionally smothered, Koistinen confessed to police that the infant died at her hands: The frazzled Mom reportedly admitted to officers that she plugged the baby’s nose and covered her mouth so that she could not breathe.

According to a probable cause statement:

During the interview, Nina admitted she smothered Maya because she thought she had too many kids already and she was jealous of the attention [her husband] was giving baby Maya. The Father . . . was put in the interview room with Nina and she admitted to him that she pinched Maya’s nose, twisted, suffocated, and smothered baby Maya.

Koistinen’s husband, Bradley, was the one to discover that the newborn was unresponsive as she lay next to his wife, so he immediately rushed her to a nearby hospital, where she was pronounced dead.

The state child protective services agency reportedly has documentation that Koistinen had mentioned in the past that she wanted to suffocate her children or wished they would have died in an automobile accident. And according to published reports, after the incident, Koistinen was allegedly quoted as saying that she wanted her children to go to heaven.

Bradley denies the statement.

Last Friday, at Koistinen’s court hearing, Bradley stood by his wife of 15 years and informed the presiding judge that she battled bipolar disorder, schizophrenia, and depression. Bradley also maintained that Koistinen never harmed their children and has been an exemplary parent, “She has been the greatest Mother . . . to our kids, never once has [she] hurt any of our kids.”

Koistinen is being held in a Phoenix, Ariz., jail on a $1 million bond.